Concrete pump

ABSTRACT

A concrete pump comprising a pair of hydraulically actuated concrete pumping cylinders, a hopper for receiving a supply of concrete to be pumped, a Y-shaped fitting including a pair of inlets and a single outlet, and a valve coacting with the concrete pumping cylinders, the hopper and the Y-shaped fitting to control the flow of concrete through the pump. The valve includes a valve body and a valve spool shiftable by a single hydraulic cylinder to alternately connect the concrete pumping cylinders to the inlets of the Y-fitting and to the hopper.

United States Patent Guddal et a1.

[ CONCRETE PUMP [72] Inventors: Karl Guddal, 6221-27th N.E., Seattle, Wash. 98115; Gunnar Guddal, 6711 5th N.W., Seattle, Wash. 98107 22 Filed: Dec. 10,1970

21 Appl. No.: 96,861

[52] US. Cl. ..417/517, 417/900, l37/625.48 [51] Int. Cl ..F04b 7/00, F04b 15/02, Fl6k 11/20 [58] Field ofSearch ..4l7/517, 900, 516, 518;

[56] References Cited UNlTED STATES PATENTS 2,125,283 8/1938 Campbell ..417/517 X FOREIGN PATENTS OR APPLICATIONS Germany ..417/900 1 Aug. 8, 1972 1,803,819 10/1968 Germany ..4l7/5l7 Primary ExaminerRobert M. Walker Attorney-Lloyd L. Zickert 57 ABSTRACT A concrete pump comprising a pair of hydraulically actuated concrete pumping cylinders, a hopper for receiving a supply of concrete to be pumped, a Y- shaped fitting including a pair of inlets and a single outlet, and a valve coacting with the concrete pumping cylinders, the hopper and the Y-shaped fitting to control the flow of concrete through the pump. The valve includes a valve body and a valve spool shiftable by a single hydraulic cylinder to alternately connect the concrete pumping cylinders to the inlets of the Y- fitting and to the hopper.

19 Claims, 25 Drawing Figures PATENTEDAus 8 m2 SHEET 1 0F 7 Inventor's Karl Guddal m Qudda 5 I fi-k ornew PATENTEDAus a me SHEU 2 BF 7' Inventors Kan-1 Gucldal Gunnar Guddal mimcnws' 8|972 SHEET 3 OF 7 1m mam. w wwu e m m m f 1 m; m G

PATFNTED B 8 I97? 3,682,575

I50 5 l5 Inventors Karl Guddal Gunnar Guddal PATENTED AUG 8 I972 SHEET 7 BF 7 Inventors Kat-l Guddal Gunnar Guddql 3 I flfisornelgs CONCRETE PUMP This invention relates in general to a concrete pump for pumping concrete from a source to a nozzle, or for pumping concrete to transport the concrete from one location to another, and more particularly to a concrete pump capable of pumping both wet and dry concrete, and still more particularly to a concrete pump having a single movable valve spool for controlling concrete flow therethrough, although the pump may also be used to pump other dense and difficult to move fluid materials.

Heretofore, there have been several concrete pumps developed, none of which could pump anything but wet concrete. For example, it has only been possible to pump concrete having a 3 to 4 inch slump with pumps heretofore known, while the pump of the invention can pump concrete having a 1 inch slump, this being much drier. It should also be recognized that the pump of the present invention can pump wetter concrete with more efficiency than heretofore known pumps. One of the problems of pumps already known lies in the fact that the concrete must move through sharp angles and narrow openings to enter the inlet side of the pump. Another problem with heretofore known pumps is the need to use a plurality of valving members and hydraulic cylinders for operating the valving members in order to accomplish pumping action. For example, one known pump utilizes four independent valves each independently powered by a hydraulic cylinder in order to accomplish the desired flow of concrete through the pump. Another known pump utilizes a flipper valve arrangement which necessitates bending the concrete around sharp corners to flow through the pump. It is not possible for dry concrete to easily bend around sharp corners.

The pump of the present invention obviates the heretofore known difficulties and enables relatively dry concrete to be pumped, such as concrete having as low as one inch slump. The pump of the invention includes a valve having a valve body and a valve spool shiftable therein and powered by a hydraulic cylinder. The valve body includes a pair of inlet ports to which are connected concrete pumping cylinders, a pair of outlet ports aligned with the inlet ports and having a Y-fitting connected thereto, wherein the Y-fitting includes a pair of inlets and a single outlet. The valve spool is movable within the valve body to coact with the inlet and outlet ports and thereby control movement of concrete therethrough. The valve spool includes a pair of opposed plates, one coacting with the inlet ports of the valve body and the other coacting with the outlet ports. The plate coacting with the inlet ports includes three openings, while the plate coacting with the outlet port includes a single opening. The tubular member extends between the single opening of the one plate and the center opening of the other plate. One of the openings in the plate having three openings, and the center opening is aligned with the inlet ports of the valve body during each of the two positions into which the valve spool may move. Accordingly, the opening in the other plate and common to the tubular member extending between the plates is alternately in communication with one or the other of the inlets to the Y-fitting, and therefore one of the outlet ports to the valve body is always closed to the hopper and valve spool, while the other is always open to the tubular member. With respect to the plate having three openings, the opening on either side of the center opening is either connected to a pumping cylinder and a hopper or is not being used. It can therefore be recognized that a single movable valve is arranged in a valve body for effecting flow control of concrete into the Y-fitting. Suitable hydraulic and electrical controls are provided for synchronously operating the concrete pumping cylinders and the valve spool. The capacity of the pump may be easily changed by changing the capacity of the concrete pumping cylinders.

It is therefore an object of the present invention to provide a new and improved concrete pump.

Another object of the invention is in the provision of a concrete pump that is simple in construction in that it has a low number of parts, and which is easily convertible for changing its capacity, and which is constructed to minimize leakage of concrete.

Another object of the present invention is in the provision of a concrete pump capable of pumping relatively dry concrete, such as concrete having as low as one inch slump.

Other objects, features, and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts, in which:

FIG. 1 is a perspective view of the concrete pump according to the invention mounted on a trailer;

FIG. 2 is a top plan view of the essentially mechanical components of the concrete pump, with some-parts broken away and other parts shown in dotted lines for purposes of clarity;

FIG. 3 is an enlarged partially fragmentary and broken view taken substantially along line 3-3 of FIG. 2 showing some parts in vertical section and other parts in side elevation;

FIG. 4 is an enlarged fragmentary sectional view taken substantially along line 4-4 of FIG. 7 through the valve with the valve spool omitted;

FIG. 5 is a broken, partly sectional and partly side elevational view taken substantially along line 5-5 of FIG. 7;

FIG. 6 is a top plan view of a stud or pin employed for providing quick detachable coupling of the pumping cylinders and Y-fitting;

FIG. 6a is a vertical sectional view taken through one of the studs mounted on the valve and illustrating a part anchored by a pin in phantom, and taken substantially along line 6A6A of FIG. 6;

FIG. 7 is a broken horizontal sectional view taken through the valve body of the valve embodiment shown in FIG. 3;

FIG. 8 is a partly diagrammatic, partly horizontal sectional view taken through the valve of FIG. 3 and illustrating the position of the movable parts when the valve spool is in one position;

FIG. 9 is a view similar to FIG. 8 but illustrating the valve spool in the other position and also showing the movable parts as they are moved to the corresponding position;

FIG. 10 is a schematic diagram of a hydraulic circuit for actuating the concrete pumping cylinders;

FIG. 11 is a broken and partly sectional view of a hydraulic cylinder employed for powering a concrete pumping cylinder, and illustrating the limit switch arrangement;

FIG. 12 is a schematic diagram of the hydraulic circuit for operating the valve spool of the valve;

FIG. 13 is an electrical schematic diagram for the solenoid actuated hydraulic valves that drive the concrete pump of the invention;

FIG. 14 is a transverse sectional view taken through a mgfilified valve wherein the spool includes a bottom w FIG. 15 is a longitudinal vertical sectional view, partly broken, and of the valve embodiment of FIG. 10, and taken substantially along line 15-15 of FIG. 14;

FIG. 16 is a transverse sectional view taken through a still further modified valve according to the invention;

FIG. 17 is a horizontal sectional view taken through a further modification of the invention and illustrating a tapered tube in the valve spool;

FIG. 18 is a front elevational view of a further modification of the invention illustrating the hopper and valve arrangement;

FIG. 19 is a top plan view of the hopper taken substantially along line 20-20 of FIG. 18;

FIG. 20 is a fragmentary enlarged. sectional view taken substantially along line 20-20 of FIG. 18, show ing the valve spool in one position;

FIG. 21 is a fragmentary enlarged sectional view taken substantially along line 21-21 of FIGS. 18 and 20;-

FIG. 22 is a fragmentary enlarged sectional view taken substantially along line 22-22 of FIG. 20;

FIG. 23 is a generally diagrammatic and somewhat sectional view of a further modified concrete pumping cylinder drive arrangement and illustrating the parts in one position; and

FIG. 24 is a view similar to FIG. 22 but illustrating the parts in another position..

Referring now to the drawings, the concrete pump of the invention is preferably mobilized to facilitate movement from one location to another, and it therefore may be mounted on a trailer or on a truck chassis. Mounting of the pump on a trailer is illustrated in FIG.

' l. The pump generally includes a pair of concrete pumping cylinders 26 and 27, a hopper 28, a Y-fitting 29, and a valve 30. The concrete pumping cylinders 26 and 27 are respectively driven by reciprocating hydraulic motors 31 and 32 in the form of hydraulic cylinders, while the valve 30 is controlled by a hydraulic motor 33 in the form of a hydraulic cylinder. An engine 34 drives one or more hydraulic pumps 35 which supplies fluid power to the hydraulic cylinders 31, 32 and 33.

Concrete is suitably supplied to the hopper 28, and operation of the concrete pumping cylinders 26 and 27 and the valve 30 causes the concrete pumping cylinders to be alternately charged with concrete and to discharge concrete. Discharge of concrete is alternately made to one of the sides of the Y-fitting 29 which is suitably connected to a flexible or rigid pipe 36, that may terminate in a nozzle 37 for the pneumatic application of concrete in a wall system or the like. Compressed air may also be supplied to the nozzle for facilitating discharge of concrete therefrom. It should be appreciated that the concrete pump may merely be used to transport concrete from one location to another. More specific operation of the pump will be hereinafter set forth in connection with the hydraulic circuits which control the hydraulic cylinders, as seen in FIGS. 10 and 12, and the synchronization of the cylinders by means of a suitable electrical circuit and switching arrangement as seen in FIG. 13.

The valve 30, details of which are illustrated in FIGS. 3, 4, 5 and 7 to 9, includes generally a valve body 40 and a valve spool 41. The valve is positioned below the hopper 28, so that concrete is fed to the valve and the valve controls the flow of concrete to the Y-fitting 29. In order to facilitate the movement of concrete from the hopper into the valve, since the hopper is tapered toward the bottom, an agitator 42 is positioned just above the valve 30 within the lower end of the hopper, and it is defined by a shaft 43 extending cross-wise of the hopper and bearingly supported in opposed hopper walls, and a plurality of fingers or tines 44 which extend from the shaft, and which are capable of moving through the concrete to maintain it in mixed form and flowable at the inlet to the valve 30. 'Asuitable rotatable fluid motor 45, FIG. 2, may be mounted on one end of the hopper and drivingly connected to the agitator shaft 43 to provide rotating power to the agitator. The fluid motor 45 may be driven from the source of the pressurized and hydraulic fluid developed by the pump 35.

The valve body 40' of the valve 30 includes a bottom wall 47, front and back walls 48 and 49, and opposite end walls 50 and 51, all arranged together to define a rectangularly shaped chamber in which the valve spool 41 is received. As seen particularly in FIG. 7, the front wall of the valve body is provided with a pair of outlet ports 52 and 53, while the back wall 49 is provided with inlet ports 54 and 55, it being appreciated that the outlet port 52 and the inlet port 54 are aligned, while the outlet port 53 and the inlet port 55 are aligned.

The outlet ports 52 and 53 are connectedto the Y- fitting 29, wherein the Y-fitting includes a pair of legs or inlets 56 and 57 merging into a single leg or outlet 58. Thus, the legs 56 and 57 become inlet members to the leg 58,- the latter of which becomes an outlet or discharge member. A single flange 59 provided at the inlet ends of legs 56 and 57 defines a mounting flange for mounting the Y-fitting to the valve front wall 48, and in this connection, the flange 59 is provided with a plurality of stud holes 60 which are received on studs 61 carried by the front wall 48.

As seen in detail in FIGS. 6 and 6a, each stud 61 is provided with a threaded portion 62 at one end which is adapted to be received in a threaded hole 63 of the valve body front wall 48. Each stud is provided with a pin opening 64 that is adapted to receive a removable pin 65 which serves to lock the flange 59 in place tightly against the valve body wall 48. Any suitable gasket may be provided between the Y-fitting flange and wall if desired to eliminate leakage and enhance the sealing relation between the flange and valve body. The pin and stud arrangement enables quick disconnect and quick connect of the Y-fitting to the valve 30. During disconnection, the pins wouldbe driven free and removed from the pin openings so that the flange and Y-fitting could easily be pulled from the studs. Similarly, when mounting the Y-fitting and flange onto the valve body, following the positioning of the flange onto the studs, the pins are inserted into the pin openings and driven into tight engagement to firmly fix the Y-fitting in place on the valve body. Accordingly, Y-fittings of various sizes can be easily substituted, and in the event of any clogging problems, the Y-fitting may be quickly and easily removed to enable cleaning and unclogging.

The concrete pumping cylinders 26 and 27 are similarly detachably fastened to the valve body 40, wherein the pumping cylinders are respectively provided with mounting flanges 68 and 69. Each pumping cylinder mounting flange includes a plurality of stud holes for receiving studs 70 that are secured to the back wall 49 of the valve body. Removable pins 71 are received in pin openings in the studs, which pins are hammered into position or removed as the "case may be when mounting or demounting of the pumping cylinders to the valve body. Accordingly, the pumping cylinders may easily be exchanged for replacements or cylinders of different capacity. Again, suitable gaskets may be provided between the valve wall and mounting flanges to seal against leakage. The pumping cylinders 26 and 27 will of course be in alignment with the inlet ports 54 and 55, while the legs 56 and 57 of the Y- fitting 29 will be in alignment with the outlet ports 52 and 53. Moreover, in the event of maintenance requirements for the pumping cylinders, they may easily be disengaged from the valve body.

The valve spool 41 may take many forms, but in the embodiment of FIGS. 1 to 9, includes front and back plates 74 and 75 of about the same height as the front and back walls of the main valve body, but of much shorter length in order to facilitate movement within the valve body. The front plate 74 includes a single opening 76, while the back plate 75 includes three openings 77, 78 and 79. The centers of the openings are at the same level as the centers of the inlet and outlet ports of the valve body. The central opening 78 in the back plate 75 is aligned with the opening 76 in the front plate 74, and a tubular member 80 extends between these openings and is suitably secured to the front and back plates, such as by welding, so that the front opening 76 and the rear central opening 78 are always in communication with each other. The outside rear openings 77 and 79 are spaced from the central opening 78 a distance equal to the spacing between the inlet ports 54 and 55 of the valve body, whereby alignment of the rear central opening 78 with one or the other of the inlet ports will cause the alignment of one or the other of the rear openings 77 and 79 with the other inlet port.

The front and rear plates 74 and 75 of the valve spool 41, are of the same length and aligned with each other, and maintained in alignment by the tubular member 80, and a plurality of connecting cross bars 81, FIGS. 2 and 3, so that the front and back plates maintain their proper position in slidable relation against the front and back walls of the valve body and move together upon being shifted from one position to the other as illustrated in FIGS. 8 and 9.

Wear plates 82 of hardened steel, FIG. 3, are epoxy glued to the engaging faces of the spool and valve body to provide long wear. They may be replaced by melting the glue and installing new plates.

In order to facilitate maintenance and to enable changing capacity of the valve, wear rings 83,FIGS. 8 and 9, may be provided for the inlet and outlet ports of the valve body, which wear rings may easily be replaced when necessary, or may be exchanged for wear rings of different size to change the inlet and outlet port size. The wear rings are merely held in place by the flanges of the pumping cylinders and Y-fittings, and the front and back plates of the valve spool. When changing'the capacity of the valve, a sleeve may be inserted in the tubular member to coact with the size of the wear n'ngs. Therefore, to change the capacity, it is only necessary to change the size of the rear rings, utilize a sleeve in the tubular member 80, and change the size of the concrete pumping cylinders.

The valve spool 41 is shifted between two positions shown in FIGS. 8 and 9 by the reciprocating fluid motor 33 in the form of a hydraulic cylinder which includes a cylinder 85 having a piston 86 therein and secured to a piston rod 87. The hydraulic cylinder 33 is double acting and may be operated by alternately connecting pressure and exhaust lines to the fluid lines 88 and 89 at opposite ends of the cylinder 85. The piston rod 87 is movable through a sealed opening 90 in end wall 50 of the valve body, and is connected at its terminal end to a fitting 91, FIGS. 8 and 9, which is in turn suitably connected to the tubular member 80 of the valve spool. Thus, actuation of the hydraulic cylinder 33 will produce shifting of the valve spool 41 between the positions shown in FIGS. 8 and 9, wherein the concrete pumping cylinders are alternately connected to the hopper so they can be charged with concrete and to one of the Y-fitting legs so that the charge can be pumped through the Y-fitting 29. As seen in FIG. 8, the pumping cylinder 26 is in its pumping or discharge stroke, and therefore in communication with the inlet leg 56 of the Y-fitting 29 through the alignment of the inlet port 54, the rear opening 78 in the valve spool, the tubular member 80, the front opening 76, the outlet port 52, and the Y-fitting leg inlet 56, while the other pumping cylinder 27 is in communication with the hopper and during it suction stroke will draw concrete into the cylinder through the rear opening 77 in the valve spool and the inlet port 55 of the valve body. Conversely, when the concrete pumping cylinders are making the opposite stroke, the pumping cylinder 26 is sucking concrete and being charged, while the pumping cylinder 27 is pumping concrete through the tubular member 80 of the valve spool and into the Y-fitting inlet leg 57, and during this cycle, the outlet port 52 is closed to the hopper. Similarly, during the previous cycle as shown in FIG. 8, the outlet port 52 is closed to the hopper by the front plate 74 of the valve spool. Therefore, it can be appreciated that while the outlet ports 52 and 53 of the valve body are alternately con nected to the concrete pumping cylinders, they are likewise alternately closed by the valve spool.

In order to facilitate cleaning of the valve 30, following the use of the pump, which may be accomplished by feeding water to the hopper and pumping it through the pumping cylinders and the Y-fitting, a drain and clean out plug 92 may be provided in the bottom wall 47 of the valve body. While not necessary, the Y-fitting 29 may also be removed during cleaning. Further, as will be hereinafter explained, the pump may be placed in reverse to draw water through the Y-fitting and back into the valve and hopper in order to expedite cleaning.

The pumping cylinders 26 and 27 operate opposite to each other, that is, when one of the pumping cylinders is in the pumping cycle, the other is in the suction cycle. The pumping cylinder 26 includes a piston slidable therein and connected to a piston rod 96, while the pumping cylinder 27 includes a piston 97 connected to a piston rod 98.

The hydraulic circuitry employed for operating the hydraulic cylinders 31 and 32 which in turn power the concrete pumping cylinders 26 and 27 is illustrated in FIG. 10. The piston rod 96 of the pumping cylinder 26 is connected directly to the piston 100 operable in the hydraulic cylinder 31, while the piston rod 98 of the pumping rod 27 is connected directly to the piston 101 operable in the hydraulic cylinder 32. Suitable seals will be provided for the piston rods 96 and 98 to prevent leakage from the concrete pumping cylinders or from the hydraulic drive cylinders, and a lubrication box 102, FIGS. 2 and 3, may be provided between the hydraulic drive cylinders and the concrete pumping cylinders to provide lubrication for the piston rods.

A four-way solenoid operated hydraulic control valve 103 alternately connects the blind ends of the hydraulic cylinders 31 and 32 to pressure and exhaust to alternately cause the concrete pumping cylinders to move through charge and discharge cycles. Lines 104 and 105 respectively connect the blind ends of the hydraulic cylinders 31 and 32 to control valve 103 which is also connected to pressure and exhaust or drain lines 106 and 107. The pump 35 in reality includes two stages, one of which is used to handle the hydraulic circuitry for the concrete pumping cylinders, and is designated 35a and the other of which is used for hydraulic circuitry handling the shifting of the valve spool 41 and which is designated 35b. The inlet end of the pump 35a is connected to the reservoir or tank 108, while the outlet or pressure side is connected to the pressure line 106. The rod ends of the hydraulic cylinders 31 and 32 are connected in common by line 109, which line is also connected through a pressure responsive valve 110 to tank 108.- Accordingly, the hydraulic fluid on the rod ends of the pistons in the hydraulic cylinders 31 and 32 is forced back and forth between the hydraulic cylinders by the pressure applied to the blind end sides of the pistons. Inasmuch as leakage will be experienced, the excess fluid at the rod ends of the pistons can be returned to tank through opening of the pressure responsive or overload valve 110 when the pressure in the common line 109 exceeds the set point of the valve 110.

The hydraulic circuitry for controlling the shifting of the valve spool 41 is illustrated in FIG. 12, wherein a four-way solenoid operated hydraulic control valve 1 12 alternately connects the rod and blind side of the piston 86 to pressure and tank. Lines 1 l3 and l 14 connect the control valve 112 to the valve spool hydraulic cylinder 33. Inasmuch as a quick and positive shifting of the spool 41 is desired, an accumulator 115 is provided for feeding pressurized fluid through the control valve 112 to the hydraulic cylinder 33. The accumulator is charged by a pump 35 through a pressure line 116. The suction side of the pump is connected to tank 117 through suction line 1 18. When the desired pressure is reached in the accumulator, an unloading valve 119 will be actuated to connect the pressure line 116 back to tank while maintaining the pressure in the accumulator. A tank line 120 is connected to the control valve 1 12. Thus, operation of the control valve 112 will cause shifting of the valve spool 41 through the operation of the hydraulic valve cylinder 33.

Electrical circuitry for synchronizing the operation of the pumping cylinders and the valve spool is illustrated in FIG. 13. It should be appreciated that any type of electrical circuitry may be provided, and further that any type of hydraulic circuitry may be employed, and that what is illustrated is typical. Each of the solenoid actuated control valves 103 and 112 include a pair of solenoids designated respectively as 103A, 1033, 112A and 1128. The circuitry of FIG. 13 includes a start switch 122, a stop switch 123, relays 124, and 126, normally open limit switches 127 and 128, and a forward-reverse switch 129. The limit switches 127 and 128 are mounted on the hydraulic cylinders 31 and 32 which power the concrete pumping cylinders 26 and 27. A typical mounting arrangement is shown in FIG. 1 1 in connection with hydraulic cylinder 31, wherein a collar 130 is provided on the common piston rod 96 to engage and drive a movable pin 131 and actuate the limit switch 127. A similar arrangement would be provided for the hydraulic cylinder 132 to actuate the limit switch 128 at the end of the pumping cycle for the respective concrete cylinder.

Power is supplied to the circuitry through terminal points 132 and 133. The stop switch 123 is normally closed while the start switch 122 is normally in open position. Momentary pressing of start switch 122 energizes relay 124 to close contacts 124a and thereby bypass the start switch 122 and hold relay 124 in energized condition. Depressing of the start switch 122 also bypasses limit switch 127 to energize relay 125 and cause closing of contacts 125a, 125b, 125C and opening v of contacts 125d. Closing of the contacts 1250 causes shifting of the control valve 103 to cause actuation of the cylinder 32 and concrete pumping cylinder 27 through its pumping cycle. The forward-reverse switch 129 is in the forward position as illustrated. Closing of contacts 125b causes a shifting of the valve spool 41 to the position whereby the pumping cylinder 27 is in communication with one side of the Y-fitting to pump concrete therethrough. Closing of contacts 1250 causes holding of relay 125 through normally closed contacts 1260, while opening of normally closed contacts 125d prevents any possible actuation of relay 126 until the limit switch 128 is closed. Upon closing of limit switch 128 by the piston rod in cylinder 32, relay 126 is energized causing opening of normally closed contacts 126a and deenergization of relay 125. Further, energization of the relay 126 causes closing of contacts 126a to operate the control valve 103 and apply pressure to the blind end of the hydraulic cylinder 31 while connecting the blind end of the hydraulic cylinder 32 to tank thereby causing the pumping cylinder 26 to move through a pumping stroke while the pumping cylinder 27 will move through a suction stroke. At the same time, contacts 126!) are closed to operate control valve 112 and shift the valve spool 41 so that the pumping cylinder 26 is placed in communication with the Y- fitting while the pumping cylinder 27 is placed in communication with the hopper. When the hydraulic cylinder 31 reaches the end of its forward travel, it will close limit switch 127 to energize relay 125 and cause deenergization of relay 126 and reverse the hydraulic control valves to cause reversal of the spool valve position and reverse movement of the concrete pumping cylinders. The cycling continues as the limit switches are alternately closed. Pumping is stopped upon opening the stop switch 123 and deenergizing relay 124 and the other one of the relays that is energized. By actuating the forward-reverse switch 129 to take the position opposite from that of FIG. 13, the relative cycling of the valve spool 41 and the pumping cylinders 26 and 27 are reversed to cause the pumping action from the Y- fitting back into the hopper.

The valve for controlling the flow of concrete between the hopper, the concrete pumping cylinders and the Y-fitting may take other forms than that shown in the embodiment of FIGS. 1 to 9 without changing the concrete flow path. It should be appreciated that the valve of the embodiment of FIGS. 1 to 9 is such that it is open at the top directly to and in communication with the lower end of the hopper so as to facilitate movement of concrete into the valve. In this respect, the valve defines the hopper bottom. Once the concrete is in the valve, it need only be sucked into one of the concrete pumping cylinders, and thereafter discharged along a straight path from the concrete cylinder through the valve spool tubular member 80 and into the Y-fitting. It should be appreciated that the concrete does not have to flow around corners in passing between the hopper and pumping cylinders, for it first gravitationally flows directly into the valve spool and then is drawn directly into one of the concrete pumping cylinders. This feature enhances the efficiency of the concrete pump and enables it to easily pump concrete of low slump.

The valve illustrated in FIGS. 14 and 15, and generally designated 137 differs from that shown in FIGS. 1 to 9 only in that the valve spool 138 includes a bottom plate 139 arranged between the front and back plates 140 and 141 so that the valve spool is further reinforced. Cross bars 142 additionally hold the front and back walls in spaced apart relation, as will the tubular member 143. The valve spool is slidably received in the valve body 144, the latter of which is of the same construction as the valve body in the embodiment of FIGS. 1 to 9. Similarly, the hopper 145 together with the Y-fitting 146 and the pump cylinders 147 are the same as in the first embodiment. Likewise, the piston rod 148 is connected at one end to the tubular member 143 and associated with a reciprocating fluid motor for shifting the valve spool within the valve body. The front and back plates 140 and 141, as well as front and back walls of the valve body are provided with the same openings as in the first embodiment. Similarly, the end edges of the front and back plates as well as the bottom plate of the valve spool are tapered to facilitate movement through the concrete received in the valve. The operation of a concrete pump having the valve of this construction is identical to that of the embodiment of FIGS. 1 to 9.

The embodiment of FIG. 16 illustrates a variation in valve construction, wherein the valve is designated by the numeral 150 and includes a valve body 151 within which is slidably arranged a valve spool 152. The valve body includes front and back walls 153 and 154, and a bottom wall 155. The front and back walls are on the outer edges of the bottom wall. A plurality of cross bars 156 extends across the front and back walls at the upper end. Both the bottom wall and the cross bars are held in place by elongated fastening bars 157. The valve spool 152 includes front and back plates 158 and 159, separated by a tubular member 160. As in the other embodiments, the front and back walls of the valve body, and the front and back plates of the valve spool include ports and openings in the same positions. The lower edges of the front and back plates of the valve spool are slidably received in longitudinally extending tracks or grooves 161 and 162 formed in the bottom wall of the valve body, while the upper ends of the plates are slidably received in tracks or grooves 163 and 164 formed in the cross bars 156, thereby guidably arranging the valve spool within the valve body. Nonnally, the cement of the concrete provides sufficient lubrication for the engaging surfaces of the valve spool and the valve body. However, when the pump is being cleaned, it may be necessary to provide further lubrication, and in that event, grease or the like may be introduced to the engaging surfaces of the valve spool and valve body by means of grease fittings I65 and 166. Any number of grease fittings may be provided along the valve body for admitting grease to the areas needing lubrication. The operation of the valve shown in FIG. 16, relative to the flow of concrete from the hopper 167 into the pumping cylinders 168 and out the Y-fitting 169 is the same as in the embodiment of FIGS. 1 to 9.

Another form of valve and pumping cylinder variation is illustrated in FIG. 17, wherein the structure is intended to permit greater pumping capacity, while at the same time maintaining compactness of the pump by maintaining a relatively short stroke on the pumping cylinders and maintaining a relatively short length on the valve, this being important from the standpoint of providing a concrete pump that can be easily transported. The valve of this embodiment is generally designated as 172, and includes a valve body 173 within which a valve spool 174 is respectably arranged. The valve body includes a front wall 175 having outlet ports 176, and a back wall 177 having inlet ports 178.

A Y-fitting 179 is secured to the front wall 172 in the same fashion as before mentioned, while pumping cylinders I80 and 181 are secured to the back wall in the same fashion as heretofore mentioned. The valve spool 174 includes a front plate 182 having a single opening 183, and a back plate 184 having openings 185, 186 and 187. The inlet and outlet ports of the valve body are sized differently as illustrated in FIG. 17 wherein the inlet ports 178 are larger than the outlet ports 176. Similarly, the valve spool openings 185, 186 and 187 in the back plate are larger than the valve spool openings 183 in the front plate. Accordingly, the velocity of concrete flow into the pumping cylinders is lower than the velocity of concrete flow into the fitting 179.

The tubular member 188 extending between the front and back plates of the valve spools is frusto-conical in shape wherein it has a larger inlet end than outlet end, the inlet end being at the back plate of the spool.

Further, the pumping cylinders include cylinder walls 180a and 1810 within which the pistons 180b and 18lb reciprocate, and the outlet ends of the cylinders are connected to the valve body by frusto-conically shaped pipe sections 189 and 190, wherein the inlet ends of the sections are larger than the outlet ends.

This embodiment is important where it is desired to increase the capacity of the concrete pump wherein the tapered tubular member 188 and the tapered pipe sections 189 and 190 permit larger pumping cylinders to be used without increasing the length of the pumping cylinders as would be necessary if the same size pumping cylinders would be employed. Further, the length of the valve need not be as long as it would have to be if the openings and ports were of a size equal to that of the pumping cylinders. It is important that the distance between the adjacent edges of the inlet ports 178 of the valve body be such that the discharge end of the tubular member 188 at the front plate of the valve spool be closed prior to the inlet end of the tubular member at the back plate but opened to the next pumping cylinder to prevent backflow of concrete from the Y-fitting into hoppers.

The embodiment of FIGS. 18-22 illustrates another form of the invention wherein the valve spool of the valve is not open directly to the hopper throughout its length, but communicates with the hopper through pipe sections. The valve, generally designated by numeral 193, includes a valve body 194 within which the valve spool 195 is reciprocably positioned. The valve spool 195 includes a front plate 196f in spaced relation from a back plate 196b, top and bottom plates l96t and 1961, and end plates 196d and l96e. Three openings 197a, l97b and 1970 are provided in the back plate 196b, and two openings 198a and 198b are provided in the front wall l96f. Openings 197a and l97b in the back plate align with openings 198a and 198b, and tubular members 199a and 1991: respectively extend therebetween. The center opening 197C communicates with an elbow 200 that also communicates with an opening 200a in the top plate 196t.

The valve body 193 includes front and back walls 201 and 202, a bottom wall 203, and a top wall 204, all arranged in box form, and closed at opposite ends by end walls 205 and 206. Inlet openings to the valve 193 are provided in the top wall by openings 207 and 208, FIG. 20, which are in communication with outlet openings 209 and 210 formed in the bottom wall 211 of the hopper 212, by means of connecting pipes 213 and 214. The inlet openings 207 and 208 in the valve are aligned with the inlet and outlet ports of the valve body, whereby charging of the concrete pumping cylinders is facilitated. The operation of the pump of this embodiment is essentially the same as that of the other embodiments, wherein the pumping cylinders are alternately charged with concrete and then discharge the concrete through a tubular member of the valve spool and the outlet Y-fitting 216.

A variation for driving the concrete pumping cylinders is illustrated in the embodiment of FIGS. 23 and 24, wherein the pumping cylinders 220 and 221 have their pistons 222 and 223 interconnected by a flexible cable 224 which extends through the rod ends of the cylinders and over a guide 225. Hydraulic fluid is pumped from a power cylinder 226 into one or the other of the pumping cylinders 220 and 221 against the cable sides of the pistons, and the power cylinder is actuated by a further hydraulic cylinder 227. The power cylinder 226 includes a cylinder 228, one end of which is in communication with the pressure chamber of concrete pumping cylinder 220 by means of a line 229, and the other end of which is in communication with the pressure chamber of the concrete pumping cylinder 221 through a line 230. A piston 231 is slidable within the cylinder 228 and provided with a piston rod 232 that is connected to the piston 233 of the hydraulic drive cylinder 227. The piston 233 of the drive cylinder 227 is slidably received within a cylinder 234 which is in a suitable hydraulic circuit for causing synchronized operation of the pumping cylinders. The hydraulic circuitry for the drive cylinder 227 is completely independent from the hydraulic circuitry for the power cylinder 226 and the concrete pumping cylinders, whereby the hydraulic fluid operating the drive cylinder 227 will not mix with that operating the power cylinder 226. Therefore, any possible leakage across the pistons of the concrete pumping cylinders, while going into the hydraulic fluid of the circuitry driving the pumping cylinders, will not affect the hydraulic circuitry for the drive cylinder 227.

In operation, as seen in FIG. 23, where the power cylinder piston 231 is driven downwardly, it pressurizes the fluid in the lower end of the cylinder and drives it into the pumping cylinder 220 to force the piston 222 downwardly to pump the concrete therefrom. Forcing the piston 222 through the pumping cycle will cause the piston 223 and the pumping cylinder 221 to go through the return stroke by the cable connection between the pistons and cause the pumping cylinder 221 to be charged with concrete. However, it should be appreciated that the vacuum created at the head end of each piston during operation of power cylinder 226 will retract the piston. Yet the connection of the pistons by cable 224 provides a more positive retraction. The low pressure fluid in the pumping cylinder 221 will be driven back into the power cylinder 226 on the low This embodiment illustrates how the overall length of the concrete pumping cylinder can be reduced by directly driving the pumping cylinders rather than driving same with hydraulic cylinders as in the other embodiments.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.

This invention is hereby claimed as follows:

1. A concrete pump comprising a hopper for receiving concrete, a pair of concrete pumping cylinders synchronously operated to be alternately charged with concrete and to alternately discharge concrete therefrom, a Y-shaped discharge fitting having a pair of inlets and a single outlet adapted to be connected to a hose, a valve arranged between said cylinders and the inlets of said fitting for alternately connecting each of the cylinders to said hopper to be charged and to said inlets of said fitting to be discharged, said valve including a valve body having a pair of inlet ports, one communicating with each cylinder, and a pair of outlet ports axially aligned with the inlet ports, one outlet port communicating with each inlet of said fitting, and a valve spool (slidably received) reciprocably movable in said valve body between first and second positions alternately connecting one of the inlet ports with one of said outlet ports and the other of the inlet ports with the hopper and closing the other of the outlet ports.

2. A concrete pump as defined in claim 1, and means for driving said concrete pumping cylinders and said valve spool in synchronism to cause pumping of concrete from the hopper to and through the Y-shape discharge fitting.

3. A concrete pump as defined in claim 1, and means for driving said concrete pumping cylinders and said valve spool in synchronism to cause pumping of concrete from the Y-shaped discharge fitting. to and into the hopper.

4. A concrete pump as defined in claim 1, wherein said valve body includes front and back opposed walls, the inlet ports being in the back wall, and the outlet ports being in the front wall, and said valve spool including spaced front and back plates interconnected to move together and respectively sliding against the front and back walls of the valve body, a single opening in the front plate adapted to be alternately in alignment with an outlet port, three openings in the back plate, the center opening being aligned with the opening in the front plate and the outside openings being spaced from the center opening a distance equal to the spacing of the valve body inlet ports, and a tubular member extending between the plates .and interconnecting the opening in the front plate with the center opening in the rear plate.

5. A concrete pump as defined in claim 4, wherein the openings in the spool plates are the same size as the valve body ports.

6. A concrete pump as defined in claim 4, wherein the inlet ports and openings in the back spool plate are larger than the outlet ports and the opening in the front spool plate, and the tubular member is frusto-conical with the large end at the back plate.

7. A concrete pump as defined in claim 6, wherein the concrete pumping cylinders have a larger outlet diameter than the valve inlet ports, and a frustoconically shaped connecting pipe extends between each cylinder and inlet port.

8. A concrete pump as defined in claim 1, wherein said valve is positioned horizontally below the hopper and effectively defines the bottom of the hopper, and said valve is fully open to the hopper throughout its length.

9. A concrete pump as defined in claim 8, wherein the valve body includes front and back opposed walls and end walls all connected to the bottom end of the hopper and a bottom wall, the inlet ports being in the back wall, and the outlet ports being in the front wall, and said valve spool including spaced front and back plates of about the same height as the front and back walls of the valve body and interconnected to move together in sliding relation along the bottom wall and respectively against the front and back walls of the valve body, a single opening in the front plate adapted to be alternately in alignment with an outlet port, three openings in the back plate, the center opening being aligned with the opening in the front plate and the outside openings being spaced from the center opening a distance equal to the spacing of the valve body inlet ports, and a tubular member extending between the plates and interconnecting the opening in the front plate with the center opening in the rear plate.

10. A concrete pump as defined in claim 9, wherein a bottom plate is provided for the spool extending between and connected to the front and back plates.

11. A concrete pump as defined in claim 9, wherein tracks are provided in the bottom wall of the valve body in which are guidably received the lower edge portions of the front and back spool plates.

12. A concrete pump as defined in claim 11, and cross bars extending between and connected to the front and back valve body walls at the upper ends, said cross bars having tracks for guidably receiving the upper edge portions of the front and back spool plates.

13. A concrete pump as defined in claim 1, wherein quick disconnect means is provided between the valve body and the concrete pumping cylinders, and between the valve body and the Y-fitting.

' 14. A concrete pump as defined in claim 1, wherein means is provided to lubricate the engaging surfaces of the valve spool and valve body.

15. A concrete pump as defined in claim 1, wherein said valve is positioned horizontally below the hopper, said valve body including front and back opposed walls and top and bottom walls and end walls all connected together to define a chamber in which the valve spool operates in coaction therewith, the inlet ports being in the back wall, the outlet ports being in the front wall, a pair of concrete supply ports in the top wall aligned with the inlet and outlet ports, said hopper including a bottom wall having a pair of discharge ports, and connecting pipes between the discharge ports and the supply ports.

16. A concrete pump as defined in claim 1, wherein each of said concrete pumping cylinders includes a cylindrical casing having a piston slidable therein between opposite ends thereof and connected to a piston rod, and means for driving the pistons of said concrete pumping cylinders including hydraulic cylinders axially aligned therewith, each of said hydraulic cylinders including a cylindrical casing having a piston slidable therein between opposite ends and connected to a piston rod of said concrete pumping cylinder.

17. A concrete pump as defined in claim 1, wherein each of said concrete pumping cylinders includes a cylindrical casing having a piston slidable therein between opposite ends thereof, means for driving the pistons of said concrete pumping cylinders including a driving hydraulic cylinder including a cylindrical casing having a piston slidable therein between opposite ends thereof and connected to a piston rod, a power cylinder including a cylindrical casing having a piston slidable therein and connected to the piston rod of said driving hydraulic cylinder, a fluid connection from each end of said power cylinder, one to each of said concrete pumping cylinders, means connecting the pistons of the concrete pumping cylinders so they move in opposite the power cylinder causes alternate movement of the 15 g l 6 directions, and hydraulicfluid in the power cylinder the spool and valve body. I r and concrete P p cylmders whereby operation of 19. A concrete pump as defined in claim I, wherein pistons in the concrete pumping cylinders. 32 ;352: 5 provlded at the Inlet and outlet ports of 18. A concrete pump as defined in claim 1, wherein 5 wear plates are provided on the engaging surfaces of 

1. A concrete pump comprising a hopper for receiving concrete, a pair of concrete pumping cylinders synchronously operated to be alternately charged with concrete and to alternately discharge concrete therefrom, a Y-shaped discharge fitting having a pair of inlets and a single outlet adapted to be connected to a hose, a valve arranged between said cylinders and the inlets of said fitting for alternately connecting each of the cylinders to said hopper to be charged and to said inlets of said fitting to be discharged, said valve including a valve body having a pair of inlet ports, one communicating with each cylinder, and a pair of outlet ports axially aligned with the inlet ports, one outlet port communicating with each inlet of said fitting, and a valve spool (slidably received) reciprocably movable in said valve body between first and second positions alternately connecting one of the inlet ports with one of said outlet ports and the other of the inlet ports with the hopper and closing the other of the outlet ports.
 2. A concrete pump as defined in claim 1, and means for driving said concrete pumping cylinders and said valve spool in synchronism to cause pumping of concrete from the hopper to and through the Y-shaped discharge fitting.
 3. A concrete pump as defined in claim 1, and means for driving said concrete pumping cylinders and said valve spool in synchronism to cause pumping of concrete from the Y-shaped discharge fitting to and into the hopper.
 4. A concrete pump as defined in claim 1, wherein said valve body includes front and back opposed walls, the inlet ports being in the back wall, and the outlet ports being in the front wall, and said valve spool including spaced front and back plates interconnected to move together and respectively sliding against the front and back walls of the valve body, a single opening in the front plate adapted to be alternately in alignment with an outlet port, three openings in the back plate, the center opening being aligned with the opening in the front plate and the outside openings being spaced from the center opening a distance equal to the spacing of the valve body inlet ports, and a tubular member extending between the plates and interconnecting the opening in the front plate with the center opening in the rear plate.
 5. A concrete pump as defined in claim 4, wherein the openings in the spool plates are the same size as the valve body ports.
 6. A concrete pump as defined in cLaim 4, wherein the inlet ports and openings in the back spool plate are larger than the outlet ports and the opening in the front spool plate, and the tubular member is frusto-conical with the large end at the back plate.
 7. A concrete pump as defined in claim 6, wherein the concrete pumping cylinders have a larger outlet diameter than the valve inlet ports, and a frustoconically shaped connecting pipe extends between each cylinder and inlet port.
 8. A concrete pump as defined in claim 1, wherein said valve is positioned horizontally below the hopper and effectively defines the bottom of the hopper, and said valve is fully open to the hopper throughout its length.
 9. A concrete pump as defined in claim 8, wherein the valve body includes front and back opposed walls and end walls all connected to the bottom end of the hopper and a bottom wall, the inlet ports being in the back wall, and the outlet ports being in the front wall, and said valve spool including spaced front and back plates of about the same height as the front and back walls of the valve body and interconnected to move together in sliding relation along the bottom wall and respectively against the front and back walls of the valve body, a single opening in the front plate adapted to be alternately in alignment with an outlet port, three openings in the back plate, the center opening being aligned with the opening in the front plate and the outside openings being spaced from the center opening a distance equal to the spacing of the valve body inlet ports, and a tubular member extending between the plates and interconnecting the opening in the front plate with the center opening in the rear plate.
 10. A concrete pump as defined in claim 9, wherein a bottom plate is provided for the spool extending between and connected to the front and back plates.
 11. A concrete pump as defined in claim 9, wherein tracks are provided in the bottom wall of the valve body in which are guidably received the lower edge portions of the front and back spool plates.
 12. A concrete pump as defined in claim 11, and cross bars extending between and connected to the front and back valve body walls at the upper ends, said cross bars having tracks for guidably receiving the upper edge portions of the front and back spool plates.
 13. A concrete pump as defined in claim 1, wherein quick disconnect means is provided between the valve body and the concrete pumping cylinders, and between the valve body and the Y-fitting.
 14. A concrete pump as defined in claim 1, wherein means is provided to lubricate the engaging surfaces of the valve spool and valve body.
 15. A concrete pump as defined in claim 1, wherein said valve is positioned horizontally below the hopper, said valve body including front and back opposed walls and top and bottom walls and end walls all connected together to define a chamber in which the valve spool operates in coaction therewith, the inlet ports being in the back wall, the outlet ports being in the front wall, a pair of concrete supply ports in the top wall aligned with the inlet and outlet ports, said hopper including a bottom wall having a pair of discharge ports, and connecting pipes between the discharge ports and the supply ports.
 16. A concrete pump as defined in claim 1, wherein each of said concrete pumping cylinders includes a cylindrical casing having a piston slidable therein between opposite ends thereof and connected to a piston rod, and means for driving the pistons of said concrete pumping cylinders including hydraulic cylinders axially aligned therewith, each of said hydraulic cylinders including a cylindrical casing having a piston slidable therein between opposite ends and connected to a piston rod of said concrete pumping cylinder.
 17. A concrete pump as defined in claim 1, wherein each of said concrete pumping cylinders includes a cylindrical casing having a piston slidable therein between opposite ends thereof, means for driving the pistons of said concrete pumpIng cylinders including a driving hydraulic cylinder including a cylindrical casing having a piston slidable therein between opposite ends thereof and connected to a piston rod, a power cylinder including a cylindrical casing having a piston slidable therein and connected to the piston rod of said driving hydraulic cylinder, a fluid connection from each end of said power cylinder, one to each of said concrete pumping cylinders, means connecting the pistons of the concrete pumping cylinders so they move in opposite directions, and hydraulic fluid in the power cylinder and concrete pumping cylinders, whereby operation of the power cylinder causes alternate movement of the pistons in the concrete pumping cylinders.
 18. A concrete pump as defined in claim 1, wherein wear plates are provided on the engaging surfaces of the spool and valve body.
 19. A concrete pump as defined in claim 1, wherein wear rings are provided at the inlet and outlet ports of the valve body. 